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REQUEST FOR A TECHNICAL REVISION FOR ADDITIONAL SPOIL DISPOSAL Background The boxcut spoil from the Colowyo mine has been placed in the Streeter Fill and a temporary fill. The Streeter Fill is included as an Experimental Mining Practice in Colowyc's February 5, 1981 major permit application. Through previous calculations it was determined that the Streeter Fill and the temporary fill would provide for sufficient volume for the box cut material if the mine was operated in a very "tight" manner. However, recent operating conditions and a re-evaluation of the requirements for a mature operation show that additional spoil material must be placed outside the mine workings to provide sufficient operating area for a safe, workable, and efficient operation. The most logical location for additional fill volume is to expand the Streeter Fill to the north. This concept was planned in the original design of the Colowyo mine, however, Colowyo was not able to obtain the rights from the surface owner to utilize this land. It now appears that Colowyo will be able to purchase this land, possibly, by May 10, 1981. Current Situation Our current mine plan is "tighter" than the space in which the mine can physically operate, and it has become apparent that the space currently available for dumping the truck/shovel spoil will be depleted by June 1, 1981. The Streeter Fill has been constructed as far as currently possible, and the pit back fill has been dumped as close to the dragline operation as is physically possible. The lack of immediate dump space has been contributed to by tie following mine life to date situations: 1. Truck/shovel over production - 2. Dragline under production - 3. Underspoiling in temporary fill - 4. Under estimate of dragline swell factor from 20 to 25 percent Total Immediate Shortfall Additional Requirements 965,000 bank cubic yards (BCY) 413,000 BCY 700,000 BCY 500,000 BCY 2,578,000 BCY In addition to the immediate shortage of dump space, Colowyo has the following needs to expand the pit to a larger configuration to eliminate future dumproom shortages, to improve safety, and to enhance operational factors: 1. Because Colowyo could not previously obtain the land to the north of Streeter Fill, there has never been any operating flexibility in the mine because of the tight dumproom constrictions. An additional 150 feet must be added to the present pit width to provide additional safety and flexibility by allowing the truck/shovel dumping to toe out on the second dragline spoil, instead of the one just being built, as is the current situation. 2. Because of the lack of dump space, all of the highwall benches were reduced to the absolute minimum width. The result of this reduction